Markerless Real Time 3D Modeling for Virtual Reality

Abstract Today, immersive environments mainly use a few 3D positions given by trackers to align the real and virtual worlds. In this paper we present an alternative approach using commodity components to achieve real time marker-less 3D modeling in virtual reality environments. The goal is to compute in real time a 3D shape of the objects and users present in the interaction space without having to equip them with markers. Having full 3D shapes opens new possibilities for full-body interactions and a tight virtual/real world integration. Data acquisition is performed through cameras surrounding the interaction space. A visual hull reconstruction algorithm is parallelized on a PC cluster to compute in real time the 3D shapes of the scene observed. Experimental results using 4 cameras and 20 processors lead to a precise 3D human model built in real time

A Distributed Approach for Real Time 3D Modeling

International audienceThis paper addresses the problem of real time 3D modeling from images with multiple cameras. Environments where multiple cameras and PCs are present are becoming usual, mainly due to new camera technologies and high computing power of modern PCs. However most applications in computer vision are based on a single, or few PCs for computations and do not scale. Our motivation in this paper is therefore to propose a distributed framework which allows to compute precise 3D models in real time with a variable number of cameras, this through an optimal use of the several PCs which are generally present. We focus in this paper on silhouette based modeling approaches and investigate how to efficiently partition the associated tasks over a set of PCs. Our contribution is a distribution scheme that applies to the different types of approaches in this field and allows for real time applications. Such a scheme relies on different accessible levels of parallelization, from individual task partitions to concurrent executions, yielding in turn controls on both latency and frame rate of the modeling system. We report on the application of the presented framework to visual hull modeling applications. In particular, we show that precise surface models can be computed in real time with standard components. Results with synthetic data and preliminary results in real contexts are presented

Modélisation tri-dimensionnelle temps-réel et distribuée

National audienceCet article traite du problème de la modélisation 3D en temps-réel à partir d'images issues de plusieurs caméras. Les environnements comportant plusieurs caméras et PC deviennent de plus en plus courants, principalement grâce aux nouvelles technologies des caméras et aux très hautes performances des PC modernes. Cependant la plupart des applications de vision par ordinateur n'utilisent qu'un seul ou un petit nombre de PC et passent mal à l'échelle. La motivation de cet article est donc de proposer un cadre distribué permettant d'obtenir des modèles 3D précis en temps-réel avec un nombre variable de caméras, ceci via une utilisation optimisée de l'ensemble des machines disponibles. Nous nous intéressons particulièrement dans cet article aux méthodes calculant l'enveloppe visuelle à partir des silhouettes et la manière de distribuer leurs calculs sur un ensemble de PC. Notre contribution consiste en une stratégie de distribution s'appliquant à différentes méthodes de ce domaine et permettant de concevoir des applications temps-réel. Cette stratégie repose sur différents niveaux de parallélisation, de la répartition de tâches indépendantes à l'exécution concurrente permettant un contrôle précis à la fois sur la latence et le débit du système de modélisation. Nous détaillons aussi l'implémentation d'une telle stratégie pour des applications de modélisation d'enveloppes visuelles. En particulier, nous montrons que des modèles surfaciques précis peuvent être calculés en temps-réel avec uniquement du matériel standard. Nous donnons aussi des résultats sur des données de synthèse et en conditions réelles

Marker-less Real Time 3D Modeling for Virtual Reality

International audienceToday, immersive environments mainly use a few 3D positions given by trackers to align the real and virtual worlds. In this paper we present an alternative approach using commodity components to achieve real time marker-less 3D modeling in virtual reality environments. The goal is to compute in real time a 3D shape of the objects and users present in the interaction space without having to equip them with markers. Having full 3D shapes opens new possibilities for full-body interactions and a tight virtual/real world integration. Data acquisition is performed through cameras surrounding the interaction space. A visual hull reconstruction algorithm is parallelized on a PC cluster to compute in real time the 3D shapes of the scene observed. Experimental results using 4 cameras and 20 processors lead to a precise 3D human model built in real time

Work Stealing for Time-constrained Octree Exploration: Application to Real-time 3D Modeling

International audienceThis paper introduces a dynamic work balancing algorithm, based on work stealing, for time-constrained parallel octree carving. The performance of the algorithm is proved and confirmed by experimental results where the algorithm is applied to a real-time 3D modeling from multiple video streams. Compared to classical work stealing, the proposed algorithm enforces a relaxed width first octree carving that enables to stop computations at anytime while ensuring a balanced carving

A practical self-shadowing algorithm for interactive hair animation

de recherch

A practical self-shadowing algorithm for interactive hair animation

Figure 1: A dynamic hair without self-shadowing (left) and shaded with our algorithm (right). The 3D light-oriented map storing hair density and transmittance (middle). The whole simulation (including animation and our rendering) is running interactively on a standard CPU. This paper presents a new fast and accurate selfshadowing algorithm for animated hair. Our method is based on a 3D light-oriented density map, a novel structure that combines an optimized volumetric representation of hair with a light-oriented partition of space. Using this 3D map, accurate hair self-shadowing can be interactively processed (several frames per second for a full hairstyle) on a standard CPU. Beyond the fact that our application is independent of any graphics hardware (and thus portable), it can easily be parallelized for better performance. Our method is especially adapted to render animated hair since there is no geometry-based precomputation and since the density map can be used to optimize hair self-collisions. The approach has been validated on a dance motion sequence, for various hairstyles. Key words: Hair self-shadowing, interactive rendering, hair simulation.

Running large vr applications on a pc cluster: the flowvr experience

In this paper, we present how FlowVR enables the development of modular and high performance VR applications running on a PC cluster. FlowVR is a middleware we specifically developed targeting distributed interactive applications. The goal of the FlowVR design is to favor the application modularity in an attempt to alleviate software engineering issues while taking advantage of this modularity to enable efficient executions on PC clusters. FlowVR relies on an extended data flow model that enables to implement complex message handling functions like collective communications, or bounding box based routing. After a short presentation of FlowVR, we describe a representative application that takes benefit of FlowVR to reach a real time performance running on a PC Cluster. 1

Parallel Adaptive Octree Carving for Real-time 3D Modeling

International audienceWe present a parallel octree carving algorithm applied to real time 3D modeling from multiple video streams. Our contribution is to propose a parallel adaptive algorithm for high performance widthfirst octree computation. It enables to stop the algorithm at anytime while ensuring a balanced octree exploration